Mutations in the protein rb can lead to cancer. how might this happen? a. mutated rb no longer phosphorylates cdk, so the inhibitory phosphate cdk is absent and cells pass immediately into m phase. b. mutated rb no longer sequesters e2f, so cells pass immediately through the restriction point and enter into the cell cycle. c. mutated rb no longer phsophorylates e2f, so transcription complexes containing e2f are perpetually activated. d. mutated rb is no longer de-phosphorylated by mapk, so it cannot be turned off and cells therefore pass immediately into m phase. e. mutated rb can no longer control the transcription of ras proteins, so the cells are continually stimulated to divide.